In general, conventional methods to correct for the Multiple Scattering (MS) errors in the Light Detection And Ranging (LiDAR) inversion have been based on existing work on bi-static imaging LiDAR. This work has uncovered that deviation in photon transport path due to multiple scattering events have both spatial and temporal effects, which can be measured with a single channel receiver system. Based on this work, state-of-the-art LiDAR imaging systems are typically configured to utilize polarization-sensitive, range-gating and model-based techniques to remove the MS contribution of the signal to improve the contrast of the target signal.
Typically, the interpretation of LiDAR return signals is based on so-called Single Scattering (SS) assumption. This theory for the interpretation of LiDAR return signals provides a solution for attenuation and backscattering inversion. However the scattering and radiative transfer theory within the basic LiDAR equation assumes that each received photon has experienced only one scattering event and therefore the backscattering information can be assumed to have resulted from a single scattering particle. However, radiative transfer in scattering media is not limited to SS, or so-called Common Volume (CV), processes. Rather, photon transport may also involve Multiple Scattering (MS) processes, also called Non-Common Volume Scattering (NCV), as well as SS processes. These scattering processes are schematically illustrated in FIG. 1. Consequently, there has been some interest in studying the combination of MS and the CV contributions in LiDAR signals in order to develop correction methods for MS “noise”, which would allow the retrieval of Inherent Optical Properties (IOPs) of the medium. These properties, particularly the attenuation coefficient and the scattering coefficient, are critical parameters used in many oceanographic applications, like underwater imaging, optical communications, underwater object detection and tracking, sensing and domain awareness, environmental monitoring and ecological health assessment.
Currently, the measurements of the IOPs are carried out with in-situ sensors, which typically utilize a very small measurement volume. Further, in order to resolve depth-dependent attenuation profiles combining depth (or range) resolved information on layers consisting of varying scattering and absorption properties, the instruments are deployed in a profiling platform and lowered through the water column. However, these methods are very slow, intrusive and ineffective when measuring dynamic events. Thus, there is a need to provide optical property information through inhomogeneous media without disturbing the measurement volume.